Merge pull request #302 from vowstar/vowstar-fix-gcc10.

Fixes build with -fno-common (default in GCC 10).

driver/cflexor.lex

@@ -27,6 +27,8 @@
 # include  "globals.h"
 # include  <string.h>
 
+char *current_file = NULL;
+
 static int comment_enter;
 static char* trim_trailing_white(char*txt, int trim);
 

driver/cfparse_misc.h

@@ -39,6 +39,6 @@ int cferror(const char *);
 int cfparse(void);
 void switch_to_command_file(const char *);
 void destroy_lexor(void);
-char *current_file;
+extern char *current_file;
 
 #endif /* IVL_cfparse_misc_H */

libveriuser/priv.h

@@ -31,6 +31,6 @@ extern char* __acc_newstring(const char*txt);
 /*
  * Trace file for logging ACC and TF calls.
  */
-FILE* pli_trace;
+extern FILE* pli_trace;
 
 #endif /* IVL_priv_H */